\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(225:1.5){A}
    \tkzDefPoint(315:1.5){B}
    \tkzDefPoint(150:1.5){C_1}
    \tkzDefPoint(95:1.5){C_2}
    \tkzDefPoint(10:1.5){C_3}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawSegments(A,B)
    \tkzDrawSegments(A,C_1  A,C_2  A,C_3)
    \tkzDrawSegments(B,C_1  B,C_2  B,C_3)
    \tkzDrawPoint(O)
    \tkzLabelPoints[above](O)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[right](B)
    \tkzLabelPoints[left](C_1)
    \tkzLabelPoints[above](C_2)
    \tkzLabelPoints[right](C_3)
\end{tikzpicture}

